This invention relates to a resin bonded abrasive tool and method of making the same.
A resin bonded abrasive tool comprises abrasive material such as fused aluminum oxide, sintered aluminum oxide, sintered sol gel microcrystalline alpha-alumina, silicon carbide, alumina zirconia, cubic boron nitride or diamond and an organic bond comprising a binder such as thermosetting resin such as epoxy resin, phenolic resin or rubber or blends thereof and a filler system. A resin bonded grinding wheel is made by mixing the abrasive material and organic bond comprising binder and filler system followed by pressing the resulting mixture into shape and typically curing the wheel at about 150 to 200.degree. C.
A abrasive tool is used for a variety of grinding and finishing applications. The ground material may be metals such as carbon steel, low alloy steel or stainless steel or non-metals such as granite, ceramic or glass. Nearly 70 to 80% of the abrasive tools contain fused aluminum oxide abrasive and are used for grinding metals, while non-metals are ground using abrasive tools containing silicon carbide grain or diamond abrasive grain.
A variety of filler systems, such as a complex salt of manganese and potassium chloride having stoichiometry of K.sub.2 MnCl.sub.6 and/or K.sub.4 MnCl.sub.6, cryolite, lithopone, iron pyrites, calcium carbonate, aluminum fluoride, iron oxide or barium sulfate or blends thereof are known to be used with resin bonded abrasive tools. Such filler systems are known to enhance the grinding performance of resin bonded abrasive tools. Examples of active fillers are described in U.S. Pat. Nos. 4,500,325, 4,877,420, 4,475,926 and 4,609,381, the contents of which are hereby incorporated by reference. The filler systems undergo physical, chemical and mechanochemical reactions due to heat generated during grinding and increase the rate of grinding or cutting the workpiece and clear the chips faster thereby improving the performance of the abrasive tool and increasing the life of the abrasive tool. Such filler systems often have limitations in manufacturing and use due to chemical and/or physical instability at the operating conditions and/or handling problems. Such filler systems are also expensive. With particular reference to the complex salt of manganese and potassium chloride, it is highly hygroscopic. Therefore, abrasive tools comprising such complex salt must be kept out of contact with atmospheric air to prevent moisture formation thereon which will adversely affect the performance and life of the abrasive tools. This makes storage of such abrasive tools difficult and inconvenient. Other filler systems are also expensive or unstable, thereby rendering abrasive tools comprising the same very expensive.
An object of the invention is to provide a resin bonded abrasive tool having improved performance and increased life.
Another object of the invention is to provide a resin bonded abrasive tool which is commercially acceptable.
Another object of the invention is to provide an efficient method of making a resin bonded abrasive tool.
Another object of the invention is to provide a method of making a resin bonded abrasive tool having improved performance and increased life.
Another object of the invention is to provide a method of making a resin bonded abrasive tool which is inexpensive.